Abstract
M.Sc. (Botany)
Cereals such as oats, rye, rice, barley, maize and wheat are a major source of food worldwide.
Wheat (Triticum aestivum L.) is the largest winter cereal crop produced in South Africa (Crop
Estimates Committee, 2011; South African Department of Agriculture, Forestry and Fisheries,
www.daff.gov.za/crop estimates). Wheat production in South Africa includes both the
summer and winter rainfall areas. Like other crops wheat is cultivated under monoculture
conditions to increase yield per hectare. This increases the risk to pathogen exposure, as
monocultures are genetically very similar or even identical, which makes them particularly
vulnerable to both abiotic and biotic stresses (Haile, 2001). Both of these stressors negatively
influence crop yield (Peterson and Higley, 2001; Wang et al., 2003).